STEM CELL TRANSPLANTATION FROM UNRELATED DONORS FOR CORRECTION OF PRIMARY IMMUNODEFICIENCIES

Allogeneic hemopoietic stem cell transplantation (HSCT) for Wiskott-Aldrich syndrome: a report of the Spanish Working Party for Blood and Marrow Transplantation in Children (GETMON)

Allogeneic stem cell transplantation is the only curative treatment for Wiskott-Aldrich syndrome. The authors retrospectively analyzed the outcome with this procedure in 13 patients with severe Wiskott-Aldrich syndrome transplanted in 5 Spanish centers from 1989 to 2006. A patient was transplanted twice from the same donor due to a late engraftment failure. Age at transplant ranged from 7 to 192 months (median 30 months). There were 10 matched donors (3 related and 7 unrelated), 2 mismatched unrelated, and 1 haploidentical. Conditioning regimen consisted of busulfan and cyclophosphamide (BuCy) in 11 cases and fludarabine and melfalan (1) or BuCy (1). ATG was added in transplants from non-genetically matched donors. GvHD prophylaxis consisted of cyclosporine and methotrexate in most patients plus T-cell depletion in the haploidentical HSCT. Nine of the 13 transplanted patients are alive with complete clinical, immunologic, and hematologic recovery 8-204 months (median 101 months) after HSCT. Eight surviving patients had been transplanted from matched donors (3 related and 5 unrelated) and 1 from a haploidentical donor. Four patients died, 2 transplanted from matched donors (1 from acute GvHD and organ failure, 1 from a lymphoproliferative disorder after a second transplant), and 2 transplanted from mismatched unrelated donors (1 from acute GvHD and organ failure, 1 from graft failure and infection). Allogeneic hemopoietic stem cell transplantation must be utilized in all patients with severe Wisckott-Aldrich syndrome, using the most suitable graft variant for each patient.

Intensive postgrafting immune suppression combined with nonmyeloablative conditioning for transplantation of HLA-identical hematopoietic cell grafts: results of a pilot study for treatment of primary immunodeficiency disorders

This study was designed to determine the safety of a nonmyeloablative regimen in patients with primary immunodeficiency disorders (PID) who had infections, organ dysfunction or other risk factors that precluded conventional hematopoietic cell (HC) transplant. Fourteen patients received HLA-matched related (n=6) or unrelated (n=8) HC grafts from marrow (n=8), peripheral blood mononuclear cells (n=5) or umbilical cord blood (n=1), either without conditioning (n=1), or after 200 cGy total body irradiation alone (n=3) or with 90 mg/m2 fludarabine (n=10). All patients were given postgrafting immunosuppression with mycophenolate mofetil and cyclosporine. Mixed (n=5) or full (n=8) donor chimerism was established in 13 patients, and one patient rejected the graft. Eight patients developed acute grade III (n=1) and/or extensive chronic GVHD (n=8). With a median follow-up of 4.9 (range, 0.7-8.1) years, the 3-year overall survival, event-free survival and transplant-related mortality were 62, 62 and 23%, respectively. Correction of immune dysfunction was documented in 8 of 10 patients with stable donor engraftment. These preliminary results indicated that this approach was associated with stable donor engraftment and a low incidence of early mortality and, thus, can be considered for certain high-risk patients with PID. However, there was a risk of GVHD, which is an undesirable outcome for this group of patients.

Non-myeloablative hematopoietic cell transplant for treatment of nonmalignant disorders in children

Hematopoietic stem cell transplantation (HCT) may offer the only curative therapy for certain life-threatening immune deficiency disorders. Conventional HCT poses a risk to patients for severe morbidity, mortality, and late sequelae resulting from myeloablative preparative regimens. This review summarizes the development of nonmyeloablative regimens that have the potential to reduce both short- and long-term risks of HCT. Results of NM-HCT in a small number of patients indicate that this procedure may play an important role in treatment of life-threatening immune deficiencies.

Nonmyeloablative hematopoietic cell transplant for treatment of immune deficiency

Hematopoietic stem cell transplantation (HCT) may offer the only curative therapy for certain life-threatening immune deficiency disorders. Conventional HCT poses a risk to patients for severe morbidity, mortality, and late sequelae resulting from myeloablative preparative regimens. This review summarizes the development of nonmyeloablative regimens that have the potential to reduce both short-and long-term risks of HCT. Results of NM-HCT in a small number of patients indicate that this procedure may play an important role in treating life-threatening immune deficiencies.

Retrovirus-mediated WASP gene transfer corrects defective actin polymerization in B cell lines from Wiskott-Aldrich syndrome patients carrying 'null' mutations

Boys affected with Wiskott-Aldrich syndrome (WAS) present with variable association of thrombocytopenia, eczema and immune deficiency. If untreated, WAS patients may succumb to intracerebral hemorrhages, severe infections or malignancies. Allogeneic bone marrow transplantation (BMT) can cure all aspects of the disease, but HLA-identical donors are not available to all patients and mismatched BMTs are unfortunately associated with high mortality and morbidity. The good success of HLA-matched BMT, however, makes WAS a potential candidate for hematopoietic stem cell gene therapy. WAS patients carry mutations of the Wiskott-Aldrich syndrome protein gene encoding WASP, a 502-amino acid proline-rich protein with demonstrated involvement in the organization of the actin cytoskeleton. To verify the feasibility of genetic correction for this disease, the WASP cDNA was expressed in EBV-immortalized B cell lines obtained from WAS patients using a retroviral vector. Transduced WAS cells showed levels of WASP expression similar to those found in cells from normal donors, without detectable effects on viability or growth characteristics. In addition, retrovirus-mediated expression of WASP led to improvement of cytoplasmic F-actin expression and formation of F-actin-positive microvilli, a process shown to be defective in untransduced WAS cell lines. These preliminary results indicate a potential use for retrovirus-mediated gene transfer as therapy for WAS.